Mattson 1985

Methods	Multicentre, randomised, parallel‐group, double‐blinded study over 10 centres in the USA with separate randomisation schemes used for each seizure type. Four treatment arms: carbamazepine, phenytoin, phenobarbitone, primidone Dates conducted: Not stated
Participants	Adults with previously untreated or under‐treated simple or complex partial or secondary generalised tonic‐clonic seizures Number randomised: PHT = 165, CBZ = 155 100% partial epilepsy. 278 (87%) men. Mean age (range): 41 (18 to 82) years Range of follow‐up: 0 to 66 months
Interventions	Monotherapy with PHT or CBZ. Median daily dose achieved: PHT = 400 mg/day, CBZ = 800 mg/day
Outcomes	Participant retention/time to drug failure (length of time participant continued to take randomised drug) Composite scores of seizure frequency (seizure rates and total seizure control) and toxicity Incidence of side effects
Notes	IPD provided for all randomised participants. All outcomes in this review calculated from IPD Funding: supported by the Veterans Adminstration Medical Research Service Cooperative Studies Program (CS 118) Conflicts of interest: None stated
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Participants randomised with stratification for seizure type. Method of randomisation not stated and not provided by authors
Allocation concealment (selection bias)	Unclear risk	No information provided in the publication or by study authors
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Double‐blind (participants and personnel) achieved using an additional blank tablet
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Unclear if outcome assessment was blinded, no information provided
Incomplete outcome data (attrition bias) All outcomes	Low risk	Attrition rates reported, all randomised participants analysed from IPD provided1
Selective reporting (reporting bias)	Low risk	All outcomes reported or calculated with IPD provided1
Other bias	Low risk	No other bias detected